The present invention relates xe2x80x9cadd onxe2x80x9d axle systems used by commercial vehicles to increase the legal weight capacity of the vehicle.
Commercial vehicles such as dump trucks often have an xe2x80x9cadd onxe2x80x9d axle to increase the legal weight capacity of the vehicle. FIG. 1 depicts a vehicle 200 having an xe2x80x9cadd onxe2x80x9d axle 202 mounted to a frame 204 of the vehicle. A tire 204 is shown mounted to the axle 202. Such conventional xe2x80x9cadd onxe2x80x9d axle systems are not without their several drawbacks. For example, conventional xe2x80x9cadd onxe2x80x9d axles do not self-track as sharply as necessary and the driver of the truck must typically raise the xe2x80x9cadd onxe2x80x9d axle in order to negotiate a turn and thereafter lowers the xe2x80x9cadd onxe2x80x9d axle to continue forward travel. Steering with such xe2x80x9cadd onxe2x80x9d axle systems may be so difficult that some drivers may only lower the xe2x80x9cadd onxe2x80x9d axle when passing an inspection station or a law enforcement officer, thereby causing a dangerous situation to the public because the load being carried by the vehicle is not adequately supported.
The primary object of the present invention to provide an xe2x80x9cadd onxe2x80x9d axle steering system to increase the legal weight capacity of the vehicle without the need for the driver to raise the xe2x80x9cadd onxe2x80x9d on axle due to lack of steering capability in both the forward and reverse direction.
The present invention is a self steering xe2x80x9cadd onxe2x80x9d axle system for use with a vehicle such as dump truck to increase the legal weight capacity of the vehicle and to provide effective steering in both the forward and revers direction. In one embodiment, the system comprises first and second hangers securely mounted to the frame of the vehicle. The system further comprises a leaf spring having first and second end portions and a bearing portion. The first end portion of the leaf spring is rotatably connected to the first hanger. The system further comprises a load adjustment member having a first end rotatably connected to the second hanger and a second end rotatably connected to the second end portion of the leaf spring. The system further comprises a stationary sleeve member securely engaged to the bearing portion of the leaf spring by a plurality of u-bolts. The system further comprises an axle rotatably disposed within the sleeve member. The system further comprises a leverage arm securely connected to the axle. The system further comprises a control system engaged with the leverage arm and operable between a first position where the king pin and the axle are positively tilted to eight degrees to provide self steering of the axle when the vehicle is moving forward to a second position wherein the king pin and the axle are negatively tilted to eight degrees to provide self steering of the axle when the vehicle is moving in the reverse direction.